Midostaurin in Treating Older Patients With Mutated Acute Myeloid Leukemia Post-Transplant

INCLUSION CRITERIA * Elderly patients with FLT3-mutated acute myeloid leukemia (AML) * Prior enrollment in Stanford study IRB-25737 * In continued complete remission * ≥ 30 days but ≤ 90 days post allogeneic hematopoietic cell transplant (HCT); treatment on this study protocol must begin before day 90 post-HCT * Absolute neutrophil count (ANC) ≥ 1000 cells/uL * Hemoglobin ≥ 8.0 g/dL and not requiring regular transfusions * Platelets ≥ 50,000 cells/uL and not requiring regular transfusions * Aspartate aminotransferase (AST) ≤ 2.5 times upper limit of normal (ULN) * Alanine aminotransferase (ALT) ≤ 2.5 X ULN * Serum bilirubin ≤ 2.5 times ULN * Ability to give written informed consent, including via legally authorized representative * Corrected QT (QTc) ≤ 450 msec * Ejection fraction (EF) ≥ 45% by 2-dimensional transthoracic echocardiography (TTE) or multiple-gated acquisition (MUGA) * Sexually active males, including vasectomized males, must agree via informed consent to use a condom during vaginal, anal, or oral intercourse, while taking midostaurin and for 5 months after stopping midostaurin * Females must have or be: * Negative pregnancy test, within 21 days of the first dose of midostaurin OR * Not of childbearing potential as follows: * Has undergone a hysterectomy or bilateral oophorectomy; * Has not had menses at any time in the preceding 24 consecutive months EXCLUSION CRITERIA * Uncontrolled acute graft-vs-host disease (GVHD) grade 3 to 4 * Uncontrolled active infection * Evidence of active AML (eg, circulating peripheral blasts on complete blood count) * Known confirmed diagnosis of human immunodeficiency virus (HIV) infection * Known confirmed diagnosis of active viral hepatitis * QTc \> 450 msec * Congenital long QT syndrome * History of presence of sustained ventricular tachycardia, history of ventricular fibrillation or torsades de pointes * Bradycardia defined as heart rate (HR) \< 50 beats per minute (bpm) * Bifascicular block (right bundle branch block plus left anterior hemiblock) * Congestive heart failure (CHF) New York Heart Association (NYHA) class 3 or 4 * Cardiac ejection fraction (EF) \< 45% within 28 days prior to starting cycle 1 * Other known malignancy (except carcinoma in situ) * Other concurrent severe and/or uncontrolled medical condition which could compromise participation in the study, eg: * Uncontrolled diabetes * Chronic active pancreatitis * Myocardial infarction within 6 months * Poorly-controlled hypertension * Chronic kidney disease * Received any investigational agent within 30 days prior to day 1 * Antineoplastic chemotherapy or radiotherapy within 28 days prior to cycle 1 * No plans for concurrent chemotherapy while on study (exception: antineoplastic drugs used as part of GVHD prophylaxis or treatment) * Any surgical procedure, excluding central venous catheter placement, bone marrow biopsy or other minor procedures (eg, skin biopsy) within 14 days of day 1 * Unwillingness or inability to comply with the protocol * Known malignant disease of the central nervous system * History of allergic reactions attributed to compounds of similar chemical or biologic composition to midostaurin * Concomitant use of strong inhibitors of cytochrome P450 family 3 subfamily A member 4 (CYP3A4) * Pregnant or lactating * Women of child-bearing potential